TBO and airworthiness

[[email protected]]

Jim Stewart > wrote:
> Does an engine past TBO make an aircraft
> non-airworthy? I can't seem to find a
> straight answer on the web.

There have been articles on avweb on the subject; search there for
details.

Short answer, for Part 91, no.

--
Jim Pennino

Remove .spam.sux to reply.

[Jim Stewart]

Does an engine past TBO make an aircraft
non-airworthy? I can't seem to find a
straight answer on the web.

[Matt Barrow[_4_]]

"Jim Stewart" > wrote in message
. ..
> Does an engine past TBO make an aircraft
> non-airworthy? I can't seem to find a
> straight answer on the web.

TBO is a manufacturers recommendation, it has noting to do w ith
airworthiness. Some aircraft are not airworthy 100 hours after TBO, while
some run well past the number.

http://www.avweb.com/news/savvyaviator/187037-1.html
The Savvy Aviator #4: Debunking TBO

Engine TBO (time between overhauls) seems to be one of the most
misunderstood concepts in aviation maintenance. There are lots of
TBO-related old wives tales that are widely believed by owners and mechanic
alike, and they can cost owners a great deal of money. Mike Busch endeavors
to clear up these misconceptions, and explain what TBO really means.

[Robert M. Gary]

On Apr 10, 9:12 pm, Jim Stewart > wrote:
> Does an engine past TBO make an aircraft
> non-airworthy? I can't seem to find a
> straight answer on the web.

Assuming you can find an IA willing to sign an annual then no.

-Robert

[Newps]

Robert M. Gary wrote:

> On Apr 10, 9:12 pm, Jim Stewart > wrote:
>
>>Does an engine past TBO make an aircraft
>>non-airworthy? I can't seem to find a
>>straight answer on the web.
>
>
> Assuming you can find an IA willing to sign an annual then no.
>

Have you found that to be a problem? I haven't. My mechanic flies his
180 on pipeline patrol and is 1000 over TBO on his 470. Another friend
also flies pipeline in his PA12 and went 3600 hours before he topped it
and 7000 hours before he finally majored it, that's a lot of 100 hour
inspections.

[Jim Stewart]

Matt Barrow wrote:

> "Jim Stewart" > wrote in message
> . ..
>
>>Does an engine past TBO make an aircraft
>>non-airworthy? I can't seem to find a
>>straight answer on the web.
>
>
> TBO is a manufacturers recommendation, it has noting to do w ith
> airworthiness. Some aircraft are not airworthy 100 hours after TBO, while
> some run well past the number.
>
> http://www.avweb.com/news/savvyaviator/187037-1.html
> The Savvy Aviator #4: Debunking TBO
>
> Engine TBO (time between overhauls) seems to be one of the most
> misunderstood concepts in aviation maintenance. There are lots of
> TBO-related old wives tales that are widely believed by owners and mechanic
> alike, and they can cost owners a great deal of money. Mike Busch endeavors
> to clear up these misconceptions, and explain what TBO really means.

Thanks. I really appreciate the link.

[Robert M. Gary]

On Apr 11, 10:16 am, Newps > wrote:
> Robert M. Gary wrote:
> > On Apr 10, 9:12 pm, Jim Stewart > wrote:
>
> >>Does an engine past TBO make an aircraft
> >>non-airworthy? I can't seem to find a
> >>straight answer on the web.
>
> > Assuming you can find an IA willing to sign an annual then no.
>
> Have you found that to be a problem? I haven't. My mechanic flies his
> 180 on pipeline patrol and is 1000 over TBO on his 470. Another friend
> also flies pipeline in his PA12 and went 3600 hours before he topped it
> and 7000 hours before he finally majored it, that's a lot of 100 hour
> inspections.

Yes, many IA's I've worked with refuse to sign after 200 over TBO. Its
probably a liability issue.

-robert

[Capt. Geoffrey Thorpe]

"Matt Barrow" > wrote in message
...
>
> "Jim Stewart" > wrote in message
> . ..
>> Does an engine past TBO make an aircraft
>> non-airworthy? I can't seem to find a
>> straight answer on the web.
>
> TBO is a manufacturers recommendation, it has noting to do w ith
> airworthiness. Some aircraft are not airworthy 100 hours after TBO, while
> some run well past the number.
<...>

So, does anyone know if TBO is based on B-10, B-50, B-90, or - what???

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[karl gruber[_1_]]

What is B-10, B50 etc?


Karl
Always top post


"Capt. Geoffrey Thorpe" <The Sea Hawk at wow way d0t com> wrote in message
...
> "Matt Barrow" > wrote in message
> ...
>>
>> "Jim Stewart" > wrote in message
>> . ..
>>> Does an engine past TBO make an aircraft
>>> non-airworthy? I can't seem to find a
>>> straight answer on the web.
>>
>> TBO is a manufacturers recommendation, it has noting to do w ith
>> airworthiness. Some aircraft are not airworthy 100 hours after TBO, while
>> some run well past the number.
> <...>
>
> So, does anyone know if TBO is based on B-10, B-50, B-90, or - what???
>
> --
> Geoff
> The Sea Hawk at Wow Way d0t Com
> remove spaces and make the obvious substitutions to reply by mail
> When immigration is outlawed, only outlaws will immigrate.
>

[Capt. Geoffrey Thorpe]

"karl gruber" > wrote in message
...
> What is B-10, B50 etc?
>
>
> Karl
> Always top post
>

B-10, B-50... are the expected hours at which 10%, 50%, etc. are expected
to fail. The "B" is from "bearing" - the orignal theorys were developed to
predict the life of ball bearings, but the termanology is now used for
everything. The Weibull distribution is usually used to "fit" durability
data and determine these values.

If TBO is B-10, then, in most cases, it would seem silly to overhaul at TBO,
if it is B-90, then it would be optimistic to expect to make TBO...

Or, TBO could be a number that some engineer pulled out of the air (to put
it politely).

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

[Matt Barrow[_4_]]

"Capt. Geoffrey Thorpe" <The Sea Hawk at wow way d0t com> wrote in message
...
> "karl gruber" > wrote in message
> ...
>> What is B-10, B50 etc?
>>
>>
>> Karl
>> Always top post
>>
>
> B-10, B-50... are the expected hours at which 10%, 50%, etc. are expected
> to fail. The "B" is from "bearing" - the orignal theorys were developed
> to predict the life of ball bearings, but the termanology is now used for
> everything. The Weibull distribution is usually used to "fit" durability
> data and determine these values.
>
> If TBO is B-10, then, in most cases, it would seem silly to overhaul at
> TBO, if it is B-90, then it would be optimistic to expect to make TBO...
>
> Or, TBO could be a number that some engineer pulled out of the air (to put
> it politely).
>

I don't think TBO is a projected or average expected "point of failure". I
believe they'd call that "Expect Life Expectancy".

[Matt Barrow[_4_]]

"Robert M. Gary" > wrote in message
ups.com...
> On Apr 10, 9:12 pm, Jim Stewart > wrote:
>> Does an engine past TBO make an aircraft
>> non-airworthy? I can't seem to find a
>> straight answer on the web.
>
> Assuming you can find an IA willing to sign an annual then no.
>

Pardon?

[Matt Barrow[_4_]]

"Robert M. Gary" > wrote in message
oups.com...
> On Apr 11, 10:16 am, Newps > wrote:
>> Robert M. Gary wrote:
>> > On Apr 10, 9:12 pm, Jim Stewart > wrote:
>>
>> >>Does an engine past TBO make an aircraft
>> >>non-airworthy? I can't seem to find a
>> >>straight answer on the web.
>>
>> > Assuming you can find an IA willing to sign an annual then no.
>>
>> Have you found that to be a problem? I haven't. My mechanic flies his
>> 180 on pipeline patrol and is 1000 over TBO on his 470. Another friend
>> also flies pipeline in his PA12 and went 3600 hours before he topped it
>> and 7000 hours before he finally majored it, that's a lot of 100 hour
>> inspections.
>
> Yes, many IA's I've worked with refuse to sign after 200 over TBO. Its
> probably a liability issue.
>

Sounds like a competency issue - on what basis did they 'fail" the aircraft?

[Dave Butler]

>> Yes, many IA's I've worked with refuse to sign after 200 over TBO.
>> Its probably a liability issue.
>>
>
> Sounds like a competency issue - on what basis did they 'fail" the
> aircraft?

They don't have to fail anything. If it's not returned to service, the
owner is at liberty to find another IA who is willing to return it to
service. An IA is not obligated to explain why he chooses not to return
an aircraft to service.

[Matt Barrow[_4_]]

"Dave Butler" > wrote in message
...
>
>>> Yes, many IA's I've worked with refuse to sign after 200 over TBO.
>>> Its probably a liability issue.
>>>
>>
>> Sounds like a competency issue - on what basis did they 'fail" the
>> aircraft?
>
> They don't have to fail anything. If it's not returned to service, the
> owner is at liberty to find another IA who is willing to return it to
> service.

Note the "" around _fail_.

> An IA is not obligated to explain why he chooses not to return an aircraft
> to service.

I seriously doubt they would stay mute on the subject.

[Dave Butler]

Matt Barrow wrote:
> "Dave Butler" > wrote in message

>> An IA is not obligated to explain why he chooses not to return an aircraft
>> to service.
>
> I seriously doubt they would stay mute on the subject.

Correct, but if the explanation is not satisfactory to the AC owner, the
IA can just say thanks for your business, next time go elsewhere.

[Matt Barrow[_4_]]

"Dave Butler" > wrote in message
...
> Matt Barrow wrote:
>> "Dave Butler" > wrote in message
>
>>> An IA is not obligated to explain why he chooses not to return an
>>> aircraft to service.
>>
>> I seriously doubt they would stay mute on the subject.
>
> Correct, but if the explanation is not satisfactory to the AC owner, the
> IA can just say thanks for your business, next time go elsewhere.

If they would not sign off my aircraft merely because it was 200 hours over
TBO, regardless of the condition of the engine, bet yer ass I'd go somewhere
else. The IA wouldn't have to ask me to go elsewhere.

[[email protected]]

On Apr 12, 8:42 am, "Matt Barrow" >
wrote:
> "Dave Butler" > wrote in message
>
> ...
>
>
>
> >>> Yes, many IA's I've worked with refuse to sign after 200 over TBO.
> >>> Its probably a liability issue.
>
> >> Sounds like a competency issue - on what basis did they 'fail" the
> >> aircraft?
>
> > They don't have to fail anything. If it's not returned to service, the
> > owner is at liberty to find another IA who is willing to return it to
> > service.
>
> Note the "" around _fail_.
>
> > An IA is not obligated to explain why he chooses not to return an aircraft
> > to service.
>
> I seriously doubt they would stay mute on the subject.

In fact, once the inspection has started, the IA is required by
FAR to sign the aircraft off as un-airworthy
and give the owner a list of things to fix to make it airworthy. Part
43.

But ahead of time, you could quiz him informally about what
he would do. If he has an idea about TBO that you don't
like, you could learn that before you start.

Bill Hale A&PIA

[Jim Stewart]

Dave Butler wrote:

>
>>> Yes, many IA's I've worked with refuse to sign after 200 over TBO.
>>> Its probably a liability issue.
>>>
>>
>> Sounds like a competency issue - on what basis did they 'fail" the
>> aircraft?
>
>
> They don't have to fail anything. If it's not returned to service, the
> owner is at liberty to find another IA who is willing to return it to
> service. An IA is not obligated to explain why he chooses not to return
> an aircraft to service.

He's supposed to make a log entry regarding the
results of his inspection isn't he? Even if the
FAR didn't specifically require such an entry,
common business ethics and practices would demand
it should the owner request it.

[Dave Butler]

>>> An IA is not obligated to explain why he chooses not to return an aircraft
>>> to service.

>
> In fact, once the inspection has started, the IA is required by
> FAR to sign the aircraft off as un-airworthy
> and give the owner a list of things to fix to make it airworthy. Part
> 43.

Oh. I'm sure you're right. Thanks for the correction. Dave

[[email protected]]

In Canada, we have it well-defined here:
http://www.tc.gc.ca/CivilAviation/Regserv/Affairs/cars/Part6/Standards/a625c.htm

Scroll down to "6. Engines" and see the note in italics. Do the FARs
have a similar requirement? I couldn't find it, but it's likely there
somewhere.
"Airworthiness" is a legal term meaning "safe and fit for
flight." Doesn't mean "perfect."

Dan

[Blanche]

Jim Stewart > wrote:
>Dave Butler wrote:
>
>>>> Yes, many IA's I've worked with refuse to sign after 200 over TBO.
>>>> Its probably a liability issue.
>>>
>>> Sounds like a competency issue - on what basis did they 'fail" the
>>> aircraft?
>>
>> They don't have to fail anything. If it's not returned to service, the
>> owner is at liberty to find another IA who is willing to return it to
>> service. An IA is not obligated to explain why he chooses not to return
>> an aircraft to service.
>
>He's supposed to make a log entry regarding the
>results of his inspection isn't he? Even if the
>FAR didn't specifically require such an entry,
>common business ethics and practices would demand
>it should the owner request it.

Beg pardon? "Common business ethics and practices" and the FARs in
the same sentence?

As another poster explained, the IA is required by the FARs to provide
a written explanation identifying each item that is unairworthy. A
log book entry is the second written documentation entry.

14CFRPart 43.11 - content, form and disposition of records for
inspection conducted under Parts 91 & 125....

(a)(5)..."...I certify this aircraft has been inspected...and a list
of discrepancies ...has been provided for the aircraft owner..."

(b)Listing of discrepancies and placards

"if the person performing any inspection required by Part 91 or 125..
finds that the aircraft is unairworthy or does not meet applicable type
certificate data, airworthiness directives or other approved data upon
which its airworthiness depends, that person must give the owner or
lessee a signed and data list of those discrepancies..."

[JB]

On Apr 12, 1:37 pm, " >
wrote:
> On Apr 12, 8:42 am, "Matt Barrow" >
> wrote:
>
>
>
>
>
> > "Dave Butler" > wrote in message
>
> ...
>
> > >>> Yes, many IA's I've worked with refuse to sign after 200 over TBO.
> > >>> Its probably a liability issue.
>
> > >> Sounds like a competency issue - on what basis did they 'fail" the
> > >> aircraft?
>
> > > They don't have to fail anything. If it's not returned to service, the
> > > owner is at liberty to find another IA who is willing to return it to
> > > service.
>
> > Note the "" around _fail_.
>
> > > An IA is not obligated to explain why he chooses not to return an aircraft
> > > to service.
>
> > I seriously doubt they would stay mute on the subject.
>
> In fact, once the inspection has started, the IA is required by
> FAR to sign the aircraft off as un-airworthy
> and give the owner a list of things to fix to make it airworthy. Part
> 43.
>
> But ahead of time, you could quiz him informally about what
> he would do. If he has an idea about TBO that you don't
> like, you could learn that before you start.
>
> Bill Hale A&PIA- Hide quoted text -
>
> - Show quoted text -

While not directly related to the engine/TBO question, I ran into this
exact problem on the recent annual for my 79 Warrior. We used a new
FBO this year (Landmark) and they took a "lets make it new" approach
on the initial inspection and estimate. The list of issues ran 3
pages long even though many had been there for many years and signed
off by 2 other smaller FBOs in previous annuals. The cost estimate
was 3x what we were used to!!

THe point being that after I recovered from heart failure over the
estimate, we considered having Landmark close it up and take it
somewhere else. But we learned that once a shop flags something as
unairworthy, its too late to "change your mind", ignore the
inspection, and start over someplace else. You can go elsewhere, but
an A&P must now sign off that the plane is safe to fly and ferry to
another shop, a FSDO has to sign off on a ferry permit, and then the
new A&P must either the fix the flagged items or note in the logbook
why he/she didn't agree with the initial diagnosis. This process
requires permits, signatures, more permits, more signatures. (In the
end, we decided it was too hard and we let Landmark suck our wallets
dry.)

--Jeff

[Matt Barrow[_4_]]

"JB" > wrote in message
oups.com...
> On Apr 12, 1:37 pm, " >
> wrote:
>> On Apr 12, 8:42 am, "Matt Barrow" >
>>
>> > I seriously doubt they would stay mute on the subject.
>>
>> In fact, once the inspection has started, the IA is required by
>> FAR to sign the aircraft off as un-airworthy
>> and give the owner a list of things to fix to make it airworthy. Part
>> 43.
>>
>> But ahead of time, you could quiz him informally about what
>> he would do. If he has an idea about TBO that you don't
>> like, you could learn that before you start.
>>
>> Bill Hale A&PIA- Hide quoted text -
>>
>> - Show quoted text -
>
> While not directly related to the engine/TBO question, I ran into this
> exact problem on the recent annual for my 79 Warrior. We used a new
> FBO this year (Landmark) and they took a "lets make it new" approach
> on the initial inspection and estimate. The list of issues ran 3
> pages long even though many had been there for many years and signed
> off by 2 other smaller FBOs in previous annuals. The cost estimate
> was 3x what we were used to!!
>
> THe point being that after I recovered from heart failure over the
> estimate, we considered having Landmark close it up and take it
> somewhere else. But we learned that once a shop flags something as
> unairworthy, its too late to "change your mind", ignore the
> inspection, and start over someplace else. You can go elsewhere, but
> an A&P must now sign off that the plane is safe to fly and ferry to
> another shop, a FSDO has to sign off on a ferry permit, and then the
> new A&P must either the fix the flagged items or note in the logbook
> why he/she didn't agree with the initial diagnosis. This process
> requires permits, signatures, more permits, more signatures. (In the
> end, we decided it was too hard and we let Landmark suck our wallets
> dry.)

http://www.avweb.com/news/savvyaviator/189710-1.html

The Savvy Aviator #18: Avoid an Annual Calamity

Pay particular attention to the part titeld, "Mismanagement Of The Annual"

[Andrew Gideon]

On Fri, 13 Apr 2007 06:02:46 -0700, JB wrote:

> But we learned that once a shop flags something as unairworthy, its
> too late to "change your mind", ignore the inspection, and start over
> someplace else.

It is not true if the previous annual has not yet expired.

- Andrew

[Andrew Gideon]

On Thu, 12 Apr 2007 22:08:32 +0000, Blanche wrote:

> As another poster explained, the IA is required by the FARs to provide a
> written explanation identifying each item that is unairworthy. A log book
> entry is the second written documentation entry.

In fact, Mike Busch recommends (and I see the reasoning) that the
discrepancy list *not* be placed in the log. There's no reason that this
information should be "preserved" at that level.

The list is required, but there's no requirement that it be logged.

- Andrew

[Andrew Gideon]

On Wed, 11 Apr 2007 06:06:53 -0700, Matt Barrow wrote:

> There are lots of
> TBO-related old wives tales that are widely believed by owners and
> mechanic alike, and they can cost owners a great deal of money.

What's amazing is that some owners are almost religious about this. That
is, it matters not what articles you put before them counting their
beliefs. They still believe.

- Andrew